Liquid crystal display (LCD) that turns images through liquid crystal molecules is widely used on many types of electronic products nowadays. In recent years as the awareness of environmental protection grows, many countries have established power saving regulations to reduce electric power consumption of electric appliances. For large organizations, enterprises or governmental institutions, the accumulating cost of using LCD panels for a prolonged period of time is significant. To address this concern, many types of power saving LCD panels have been developed on the market. For instance, R.O.C. patent publication No. 580681 discloses a power saving LCD which performs display by receiving a multi-level operation voltage. It includes an upper baseboard consisting of an upper electrode and an ½ wave plate, a lower baseboard consisting of a lower electrode and a liquid crystal layer located between the upper electrode and the lower electrode. When the liquid crystal molecules in the liquid crystal layer is in a first stable condition, the multi-level operation voltage controls transmittance of the liquid crystal layer, and the liquid crystal layer is equivalent to ¼ wave plate. A signal generator also is provided to be electrically connected to the upper electrode and the lower electrode to generate a switch signal to the upper electrode and the lower electrode so that the liquid crystal molecules in the liquid crystal layer can be switched from the first stable condition to a second stable condition to give the liquid crystal layer a constant transmittance.
However, the power saving LCD panel mentioned above has a complicated structure and is difficult to fabricate. It also has to use special materials to form the liquid crystal layer. As a result, the cost of the LCD panel is higher. How to provide a simpler power saving structure for LCD panels without increasing the cost too much is a big issue in the industry.